Radiotelephone system



J. H. PAYNE, 1R-

RADIOTELEPHONE SYSTEM.

APPLICATION FILED Aue.28. 1916.

1,313,1 12. Patented Aug. 12, 1919.

/4 Inventor /4 His Attorney.

John H .Pa ne Jr;-

UNITED STATES PATENT oE IoE.

JOHR H. PAYNE, J'Bh, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RADIOTELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Aug; 12, 1919.

To all whom it may concern:

Be it known that I, JOHN H. PAYNE, Jr., a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certaln new and useful Improvements in Radiotelephone Systems, of which the following is a specification.

My present invention relates to wireless signaling systems, and more particularly to a wireless telephone system in which an electron discharge device is utilized for producing high frequency alternating currents for transmitting signals.

It has been well known for some time that an electron discharge device comprising a cathode, capable of emitting electrons, a cooperating anode and a discharge controlling member or grid, all inclosed in an evacuated receptacle, can be utilized to produce high frequency alternating currents. Such a result is obtained by suitable coupling of an external circuit which includes the cathode and anode with a second circuit which includes the cathode and grid. By varying the potential of the grid the current between cathode and anode is caused to pulsate and this pulsating current will give rise to an alternating current in another circuit suitably coupled thereto.

Devices of this nature as previously constructed have been adapted to carry only comparatively small currents and hence in order to derive large amounts of high frequency energy it is necessary to use a comparatively high potential source of current in the circuitbetween cathode and anode, which for convenience in description, has been designated the plate circuit. In order to utilize the currents thus produced for obtaining a modulated high frequency current for transmitting signals produced by sound waves, it .has been proposed to superimpose upon the circuit which includes the cathode and the grid, telephone currents which are produced by the sound waves which it is desired to transmit. This method of control has not been found to be entirely practical however because of the fact that when the potentials which are obtained from the telephone currents are large enough to secure an eflicient control of the modulation of the signaling current the device tends to become unstable and stop oscillating. For the most eflicient control of the signaling current for the transmission of signals it is desirable that this current should be caused to vary between the maximum value and zero. Such control, however, is not easy to secure by the method referred to because of the above mentioned difficulty, and also because of the fact that it is not usually convenient to obtain potentials of the same order of magnitude from! telephone currents as those which may be used on the grid for producing oscillations.

The object of my invention is to overcome these difliculties and provide an eflicient system for modulating the high frequency current in which the desired range of control may be secured by means of a single device of the general type referred to.

In carrying my invention into effect] utilize a device comprising the usual cathode, anode and grid, and a second grid which may be operated entirely independently of the first grid. The high frequency current is produced by coupling the circuit which includes one of these grids with the plate circuit and the modulation of the current is secured by applying the potentials obtained from the telephone currents to the second grid. By proper design of the tube the control exercised by this second grid may be of the same order of magnitude as the control exercised by the first grid almuch less than those acting upon the first grid.

My invention will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 shows a device which may be utilized for carrying my invention into effect, and Fig. 2 shows diagrammatically the circuit connections which may be employed.

The device shown in Fig. 1 comprises an evacuated receptacle 1' inclosing a cathode 2, which is preferably a filament of tungsten connected to leading-in conductors 3 by means of .which current may be supplied for heating it to incandescence to cause it to emit electrons, a discharge controlling member or grid 4 consisting of two metal frames 5 on each side of the cathode and wires 6 wound upon these frames.v Anodes 7 are also provided on each side of the cathode. The grid 4 is connected to leading-in conductor 8 and the anodes 7 to leading-in conductors 9. While in the construction shown these anodes are entirely separate they may be connected together externally and operated as a single electrode. The frame work 10 which supports the cathode also supports a second grid 11 consisting of a fine wire wound back and forth upon the frame work in such a manner that it surrounds the cathode. This grid is connected to leadingin conductor 12. The receptacle 1 is preferably exhausted to such a degree that with any operating voltage which may be employed the flow of current between the else trodes is not accompanied by an visible manifestation of gas ionization, sue for example, as blue glow.

Connections which I prefer to use in carrying my invention into effect are indicated in Fig. 2. As here shown the battery 13 supplies current for heating the cathode 2 to incandescence and an external circuit between cathode and anode includes a source H of direct current and an inductance 15, which may be coupled by the inductance 16 to antenna 17. The circuit between cathode and grid 4 includes an inductance 18. The two last described circuits are coupled to some extent by the electrostatic capacity between the electrodes. An additional coupling, however, is preferably furnished by the variable condenser 19 which is connected between anode 7 and grid 4. The frequency of the current produced may be varied by varying this condenser. The direct current source 14 is preferably shunted by a condenser 20 in order to by-pass the high frequency component of the current flowing in the plate circuit. Current for modulating the signals is furnished by the local circuit of a telephone transmitter 21 and potentials derived from this current are applied to the grid 11 by means of the transformer 22 as indicated. As long as there is no variation in the current flowing in the local circuit of the telephone 21 the potential of the grid 11 will be constant, and this grid will play no part in the operation of the device as a self excited oscillation generator. Under these conditions high frequency currents will be produced in the antenna in a well known manner. As soon, however as the current in the local circuit of the telephone 21 varies, the potential of grid 11 will vary and there will be a corresponding variation in the current flowing in the plate circuit of the device. Apparatus of this type may be so designed that a smaller otential variation upon this grid will be su cient to vary the current in the plate circuit between a maximum and zero than that required upon the grid 4. Hence, while a variation of several hundred volts upon the grid 4 may be desirable to secure a maximum output of high frequency current, a much smaller potential variation L upon the grid 11 may be sufiicient to vary the current flowing in the plate circuit between a miximum and zero.

While I have illustrated one form of device which is suitable for carrying my invention into effect, it will be apparent that many modifications in the specific form and design of the apparatus used may be made, and also that various modifications in the circuit arrangement employed may be utilized in carrying my invention into effect without departing from the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination in a wireless signaling system of an antenna, an electron discharge device comprising a cathode, an anode and two grids inclosed in an evacuated rece tacle, a circuit inductively coupled to sald antenna which includes said cathode and anode and a source of ener y, a second circuit electrostatically couple to the first circuit which includes the cathode and one of the girds whereby the device acts as a self excited oscillation generator, a third circuit including the cathode and second grid, and a telephone circuit inductively related to the third circuit.

2. The combination in a wireless signaling system of an antenna, an electron discharge device comprising a cathode, an anode and two. grids, inclosed in an evacuated receptacle, a circuit coupled to the antenna which includes said cathode and anode and a source of energy, a second circuit including the cathode and one of the grids coupled to the first circuit by a variable electrostatic coupling in such a way that high frequency currents will be induced in the antenna by the action of the device as a self excited oscillation generator, a third circuit including the cathode and second grid, and means for impressing a signaling current upon the third circuit.

3. The combination in a wireless signaling system of an antenna, an electron discharge device comprising a cathode, an anode and two grids inclosed in an evacuated receptacle, one of said grids being located at a greater distance from the cathode than the other, a circuit inductively coupled to said antenna which includes said cathode and anode and a source of energy, a second circuit coupled to the first circuit and which includes the cathode and the grid which is farthest from the cathode, a third circuit including the cathode and the grid nearest the cathode, and a telephone circuit inductively related to the third circuit.

4. The combination in a wireless signaling system of an antenna, an electron discharge device comprising a cathode, an anode and two grids inclosed in an evacuated receptacle, one of said grids being located at a greater distance from the cathode I circuit.

circuit coupled to than the other, a circuit operatively related to said antenna which includes said cathode and anode and a source of energy, a second circuit which includes the cathode and the grid which is farthest from the cathode, means for varying the potential of the grid of said second circuit at radio frequency, a third circuit including the cathode and the grid nearest the cathode, and a telephone circuit inductively related to the third 5. The combination in a wireless signaling system of an antenna, an electron discharge device comprising a cathode, an anode and two grids inclosed in an evacu-' ated receptacle, one of said grids being located at a greater distance from the cathode than the other, a circuit inductively coupled to said antenna which includes said cathode and anode and a source of energy, a second the first circuit and which includes the cathode and the grid which is farthest from the cathode, a third circuit including the cathode and the grid nearest the cathode,'and means for impressing a low frequency signaling current upon the third circuit.

6. The combination in a wireless signaling system of an antenna, an electron discharge device comprising a cathode, an anode and two grids inclosed in an evacuated receptacle, one of said grids being located at a reater distance from the cathode than the ot er, a circuit operatively related to said antenna which includes said cathode and anode and a source of energy, a second circuit which includes the cathode and the grid which is farthest from the cathode,

means for varying the potential of the grid of said second circuit at radio frequencies, a

a third circuit including the cathode and the grid nearest the cathode, and means for impressing a low frequency signaling current upon the third circuit.

- 7. The combination in a system for producing. modulated radio frequency currents of an electron discharge device comprising a cathode, an anode and two grids inclosed in an evacuated receptacle, one of said grids being located at a greater distance from the cathode than the other, a circuit which includes said cathode and. anode and'a source a of energy, a second circuit which includes the cathode and the grid which is farthest from the cathode, means for varying the potential of the grid of said second circuit at radio frequencies, a third circuitincluding the cathode, and a telephone circuit inductively related to the third circuit.

8. The combination in a system for producing modulated radio frequency currents of an electron discharge device comprising a cathode, an anode and two grids inclosed in an evacuated receptacle, one of said grids being located at a greater distance from the cathode than the other, a circuit which ineludes said cathode and anode and a source of energy, a second circuit which includes the cathode and the grid which is farthest from the cathode, means for varying thepotential of the grid of said second circuit at radio frequencies, a third circuit including the cathode and the grid nearest the cathode, and means for impressing a low frequency modulating current upon the third circuit.

In witness whereof, I have hereunto set my hand this 25th da of August, 1916.

JOI-l N H; PAYNE, Jr.

cathode and the grid nearest the 

